control-spec.txt changes for #2411 specify wrong version

My torspec.git branch for my legacy/trac#2411 (moved) changes specified that the BUILD_FLAGS, HS_STATE, and REND_QUERY fields were introduced in 0.2.3.2-alpha; they won't be introduced until 0.2.3.11-alpha.

[https://gitweb.torproject.org/torspec.git/blobdiff/06a4623955e4111553173c4d5210e55e8979e981..50c33cb3591eaa15afa1948e1c926381d9963ff4:/control-spec.txt]